Pro-Slavery Republican Poll Debunked

In USA Today, David Mastio has a nice dissection of a Times article about a poll purporting to show that "Nearly 20 percent of Mr. Trump's voters disagreed with Abraham Lincoln's Emancipation Proclamation." Mr. Mastio writes:

Originally, Vavreck, the Times and YouGov only reported on the racially insensitive views of Republicans, failing to publish or even analyze the responses of potential Democratic voters. Vavreck only performed the Democratic analysis and released it to me on Friday after YouGov refused to release the data on Thursday and I contacted YouGov's European executives, its in-house polling expert and Vavreck herself.